The invention generally relates to mixing devices and particularly to those known as motionless mixers. The invention also relates to methods of mixing fluid-like materials and, in a particular embodiment, to a combustion engine system capable of producing a mechanical output in response to combustion of a combined fluid-like material input thereto.
The mixing of relatively stationary fluids, for example in a mixing container, may be carried out by a moving mixing blade or the like. Such movable mixers, however, are bulky, require large power inputs, and are difficult to adapt to use in fluid systems in which continuously flowing fluids are to be mixed. However, a number of so-called motionless mixers are available for the purpose, as disclosed, for example, in U.S. Pat. Nos. 3,923,288; 3,583,678 and 3,860,217. In the former patent a plurality of flow dispersing or interrupting elements are placed in a relatively long tubular housing to form a mixing matrix for turbulently mixing the fluid flowing therethrough. In the latter two patents the main flow stream through a relatively long tubular housing is divided into several discrete flow streams that flow through separate passageways. The positional relationship of the divided flow streams where they initially divide and where they exit the dividing elements is altered for enhanced variation in the interfacial surface contact between flow streams. Where the flow streams exit such a dividing element, they mix turbulently and then enter a further dividing element until finally the mixed fluid exits the device.
The known theory of stratification for interfacial surface generators, such as the one disclosed in U.S. Pat. No. 3,583,678, follows the equation S=N(X).sup.Y ; where S is the stratification or number of individual strata produced by the mixing apparatus; N is the number of components being mixed; X is the number of streams produced by each dividing element of the mixing device; and Y is the number of dividing elements in the housing of the mixing apparatus. The larger the value S, the larger the number of strata produced by the mixing device and, accordingly, the more homogeneous is the mixture produced thereby.
The foregoing and other examples of motionless mixers for continuously flowing fluids are relatively large and cumbersome, relatively expensive, and in many cases unsatisfactory for producing long-lasting, homogeneous mixtures.
As used herein the term fluid of fluid-like means a material that is capable of flowing, such as, for example, a liquid, a gas, or even a solid that has satisfactory flow characteristics or is carried in a fluidic carrier; for example, such materials may be a pigment for mixing in a paint, a polymer being mixed to facilitate polymerization, etc. The present invention, however, although capable of and intended to effect mixing of various media, will be described in detail below with reference to the mixing of water and gasoline to form an emulsion that is consumed in a combustion engine.
In the past, one technique for combining water and gasoline or other combustible fuel to be burned in a combustion engine, such as in an aircraft engine, employed the direct injecting of small quantities of water into the fuel. However, as fas as is known by the applicant, no substantial mixing of the water and fuel was effected.
In present day combustion engines such as an internal combustion engine used in an automobile, it is common to burn an overly rich mixture, i.e. larger than the optimum fuel air mixture for complete combustion, so there is some unburned vapor remaining in the products exhausted from a cylinder. That unburned vapor provides an important function of cooling the exhaust products to avoid excessive damaging heat at the exhaust valve and/or rest of th exhaust system. For fuel economy, though, it would be desirable to burn an effectively leaner mixture having a lower percentage of fuel.